用配方法解下列方程：3x²+8x+1=0 2x²-7x+3=0 -3x+4x+1=0

(1) 3x²+8x+1=0(x²+2*4/3x+1/3)=0(x²+2*4/3x+16/9 + 1/3-16/9)=0(x+4/3)² = 13/9x = -4/3 ± 1/3√13(2) 2x²-7x+3=0x²-7/2x+3/2=0x²-2*7/4x+49/16+3/2-49/16=0(x-7/4)² = 2...